a) Field of the Invention
The present invention relates to an automatic vehicular velocity control apparatus for an automotive vehicle to follow up a preceding vehicle which is running ahead of the vehicle at an appropriate inter-vehicle distance when the preceding vehicle has been recognized.
b) Description of the Related Art
A Japanese Patent Application First Publication No. Heisei 11-59222 published on Mar. 12, 1999 exemplifies a previously proposed automatic vehicular velocity control apparatus to follow up a preceding vehicle which is running ahead of the vehicle at the same traffic lane at an appropriate inter-vehicle distance.
In the above-described control apparatus, a preceding vehicle follow-up run control system is constituted by an inter-vehicle distance control system and a vehicular velocity control system. A first gain fd by which an inter-vehicle distance deviation xcex94L is multiplied and a second gain fv by which a relative velocity xcex94V of the vehicle to the preceding vehicle is multiplied are set on the basis of a specific angular frequency xcfx89M and a damping factor xcex6M in a transfer function of the preceding vehicle follow-up run control system, a target relative velocity V* is calculated as follows: xcex94V*=(fdxc3x97xcex94L+fvxc3x97xcex94V), and a target vehicular velocity V* is calculated by subtracting the target relative velocity xcex94V* from the vehicular velocity VT of the preceding vehicle.
Then, if both of the first gain fd and the second gain fv are modified according to the detected value of the inter-vehicle distance, the response characteristic of the inter-vehicle distance control system is modified.
However, since the response characteristic of the inter-vehicle distance control system is modified only by means of the detected value of the inter-vehicle distance, the following problems occur in the previously proposed automatic vehicular velocity control apparatus described in the BACKGROUND OF THE INVENTION.
(1) Suppose that the vehicle has recognized the preceding vehicle at an inter-vehicle distance sufficiently longer than a set inter-vehicle distance and is about to approach to the preceding vehicle whose vehicular velocity is lower than that of the vehicle up to the set inter-vehicle distance. An abrupt deceleration is, in this case, carried out immediately after the preceding vehicle has been recognized even when the relative velocity of the vehicle to the preceding vehicle is large and the inter-vehicle distance when the preceding vehicle has just been recognized is sufficiently longer than the set inter-vehicle distance so that a vehicular run disagreeable to a vehicular occupant(s) occurs.
(2) Suppose that another vehicle has been interrupted into a spatial interval of a traffic lane between the preceding vehicle and the vehicle during the follow-up run of the vehicle to the preceding vehicle. Since the inter-vehicle distance between the other vehicle and the vehicle becomes abruptly shorter than the set inter-vehicle distance, the abrupt deceleration is carried out immediately after the interruption of the other vehicle to the spatial interval between the old preceding vehicle and the vehicle although the relative velocity of the vehicle to the other interrupting vehicle is almost zero.
(3) Furthermore, suppose that the vehicle itself has made a traffic lane change from a normal traffic lane on which the preceding vehicle was running ahead of the vehicle to an overtake traffic lane on which an overtake vehicle is running ahead of the vehicle and the vehicle is to follow up the overtake vehicle which is the new preceding vehicle.
If the inter-vehicle distance to the new preceding vehicle is shorter than the set inter-vehicle distance, the abrupt deceleration of the vehicle is also carried out immediately after the follow-up run of the vehicle to the new preceding vehicle even if the vehicular velocity of the new preceding vehicle is higher than that of the vehicular velocity so that the vehicular run disagreeable to the vehicular occupant(s) occurs.
It is therefore an object of the present invention to provide an improved automatic vehicular velocity control apparatus for an automotive vehicle which can achieve a smooth start for the vehicle to appropriately follow up a preceding vehicle which is running ahead of the vehicle with no driving anxiety given to the vehicular occupants with an avoidance of the abrupt deceleration described above.
According to one aspect of the present invention, there is provided with an automatic vehicular velocity control apparatus for an automotive vehicle, comprising: an inter-vehicle distance detector to detect an inter-vehicle distance from the vehicle to a preceding vehicle which is running ahead of the vehicle; a vehicular velocity detector to detect a vehicular velocity of the vehicle; a relative velocity detector to detect a relative velocity of the preceding vehicle to the vehicle; an inter-vehicle distance command value calculator to calculate a command value of the inter-vehicle distance; a control response characteristic determinator to determine a control response characteristic of an inter-vehicle distance control system in accordance with to a deviation between the command value of the inter-vehicle distance and a detected value thereof and a detected value of the relative velocity; a vehicular velocity command value calculator to calculate a command value of the vehicular velocity on the basis of the determined control response characteristic of the inter-vehicle distance control system; and a vehicular velocity control section to control at least one of a driving force of the vehicle, a braking force of the vehicle, and a gear ratio of a vehicular transmission in such a manner that a detected value of the vehicular velocity is made equal to the command value of the vehicular velocity.
According to another aspect of the present invention, there is provided with an automatic vehicular velocity control apparatus for an automotive vehicle, comprising: an inter-vehicle distance detector to detect an inter-vehicle distance from the vehicle to a preceding vehicle which is running ahead of the vehicle; a vehicular velocity detector to detect a vehicular velocity of the vehicle; a relative velocity detector to detect a relative velocity of the preceding vehicle to the vehicle; an inter-vehicle distance command value calculator to calculate a command value of an inter-vehicle distance; a target value determinator to determine a target value of the inter-vehicle distance prescribing a variation of the inter-vehicle distance with time until the detected value of the inter-vehicle distance has reached to the command value of the inter-vehicle distance; a gain determinator to determine a first gain by which a deviation between the target value of the inter-vehicle distance and the detected value of the inter-vehicle distance is multiplied in accordance with the detected value of the relative velocity; a vehicular velocity command value calculator to calculate a command value of the vehicular velocity to make the detected value of the inter-vehicle distance equal to the target value of the inter-vehicle distance on the basis of the detected value of the vehicular velocity, the detected value of the relative velocity, and the deviation between the target value of the inter-vehicle distance and the detected value thereof; and a vehicular velocity control section to control at least one of a driving force of the vehicle, a braking force of the vehicle, and a gear ratio of a vehicular transmission in such a manner that the detected value of the vehicular velocity is made equal to the command value thereof.
This summary of the invention does not necessarily describe all necessary features so that the present invention may also be a sub-combination of these described features.